The present invention relates to a controlled compliance rotor winding support block. More particularly the support block will allow the control and minimization of coil expansion forces exerted on the rotor forging of a turbine generator. This control is accomplished by the use of a non-conducting spring captured within a non-conducting block assembly.
Service reliability problems have been encountered with prior art support blocks. Support blocks in the prior art fit tightly between the rotor coils and the adjacent rotor steel. With this tight fit, low support block, high thermal expansion forces are transferred from the copper windings to the main shaft forging. These forces cause the main forging to bend causing increased unbalance with increased temperature. This thermal unbalance forces operators to reduce load or remove the unit from service.
The invention overcomes the problems in the prior art resulting from using rigid tight fitting blocks which cause thermal vibration problems and a continuing source of unit unavailability and economic loss. The invention solves the prior art problems by providing a robust, retrofit compliant block to the generator fleet which allows for thermal expansion while in service and thereby eliminates thermal unbalance.
In particular, a spring is used to compensate for the thermal expansion of the copper windings. The spring fits within a recess or pocket of one part of the block assembly and is held in place by the other part of the block assembly.